The present invention relates to robots and, also, to apparatus for composing video source material.
In the production of audiovisual films, videos, television commercials, movies, and the like, a video camera is used to record video images and/or audio signals on a video tape. The video tape may be carried directly by the camera, as in a video camcorder, or the video images from a video camera may be output to a video tape recorder (VTR) which records the video images on a video tape. The video tape can then be played back to review the recorded images.
As frequently occurs during the production of audiovisual materials, it is oftentimes necessary to re-shoot some portion of the recorded sequence of images. When this occurs, the video tape must be rewound to the desired position or frame to enable new video images to be recorded over old images or new video images are recorded on a separate tape. After the new and old images are recorded on different tapes, the two video tapes are then edited by merging the desired portions of the two tapes into a single tape to form the desired sequence of video images. A number of video tape editing devices are available to perform such editing operations.
Time code generators are also well known and are used to generate standardized time codes. Such time codes are developed according to standards set by the SMPTE (Society of Motion Picture and Television Engineers) and the EBU (European Broadcasting Union). The time codes are formed of a binary code corresponding to hours, minutes, seconds and frame number of each frame of a video signal starting from a zero point and continuing during the entire video image running time. The time code information is encoded onto a recording medium by a video tape recorder on a separate track from the tracks containing the video information for each frame of the video signal. The recorded time code information acts as an address to identify each frame to permit electronic editing of video tapes.
During editing, time code readers are employed to locate a particular frame on a video tape. However, such editing is a time consuming process requiring a considerable amount of skill and costly time code generators, time code readers and tape synchronizers which result in high post production costs to form a complete audiovisual tape.
As described above, it is often necessary during the production of audiovisual material to re-shoot the same sequence of images many times before a final sequence is obtained. The camera and/or the object(s) being filmed must be moved through the same path of movement with only the desired variations being introduced in each separate re-shoot. Various devices have been employed to repeatedly move an object and/or camera through a predetermined path.
Robots have been developed, primarily for industrial applications, to move a tool, etc., mounted at the end of an end effector on a robot arm in a predetermined multi-axis path of movement according to a stored program executed by a robot controller.
It is known to mount a camera on the movable arm of a robot so as to be able to repeatedly move the camera through a predetermined path of movement while the camera is operated to record a sequence of video images. However, heretofore, there has been no known attempt to synchronize the movement of the robot as it executes its stored control program with the advance or reverse movement of a video recording medium storing video images in a predetermined sequence to enable the robot and the recording medium to be moved in synchronization to a predetermined position corresponding to a particular frame on the video tape with the robot being positioned in the same position as it was while the image was shot. The different speeds of the film transport in the video camera and/or video tape recorder and the motors controlling the position and speed of movement of the robot arm have made such synchronization difficult and have resulted in hit or miss efforts to position a robot in a particular position in multiple axes corresponding to a particular robot position in a particular frame on a video tape.
Thus, it would be desirable to provide an apparatus for synchronizing robot or machine movement with a video recording medium such that the robot or machine can be positioned in the same position as recorded on each frame of the video tape. It would also be desirable to provide an apparatus for use with a robot or machine and a video recording apparatus which enables the robot arm to be moved to any position corresponding to a particular frame of a recorded video image while remaining synchronized in time with the video recording.